Everything below concerns cyclic heptapeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
The brick, five-story Folger Coffee Company Building at 101 Howard in San Francisco, California is the former headquarters of Folgers. It is listed on the United States National Register of Historic Places. The building still has a sign saying "The Folgers Coffee Company" on one corner. On August 2, 2011, the Folger Building was purchased by the University of San Francisco, marking a return to the university's roots in downtown San Francisco.
This list contains a list of EC numbers for the second group, EC 2, transferases, placed in numerical order as determined by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology. All official information is tabulated at the website of the committee. The database is developed and maintained by Andrew McDonald.
Robert Harold "Bobby" Liebling (born December 21, 1953) is an American musician. He is the founder, lead vocalist, and only continuous member of the pioneering doom metal band Pentagram. He has been referred to as "very much the U.S. version of Ozzy Osbourne, but without the money or sustained success." His life and struggles with addiction were documented in Last Days Here (2011).
=== Lesbian culture === Violets became symbolically associated with romantic love between women. This connection originates from fragments of a poem by Sappho about a lost love, in which she describes her as "Close by my side you put around yourself [many wreaths] of violets and roses." In another poem, Sappho describes her lost love as wearing "violet tiaras, braided rosebuds, dill and crocus twined around her neck". In 1926, one of the first plays to involve a lesbian relationship, La Prisonnière by Édouard Bourdet, used a bouquet of violets to signify lesbian love.
Sources: en.wikipedia.org
The bank did hedge against interest rate risk on its available-for-sale portfolio by building up a portfolio of $15.2 billion of interest rate swaps by the end of 2021. At the same time, startup companies withdrew deposits from the bank to fund their operations as private financing became harder to come by. A series of layoffs in the technology sector that began in 2022 also caused depositors to draw down their savings. During the first half of 2022, the bank realized $517 million in gains by unwinding $11 billion of its interest rate swaps on its available-for-sale bond portfolio. By the end of the year, it had only $563 million in swaps protecting that portfolio. In early 2023, to raise needed cash to fund withdrawals, the bank sold all of its available-for-sale securities, realizing a $1.8 billion loss. The bank was criticized for timing its announcement shortly after Silvergate Bank, which catered to cryptocurrency users, started winding down its operations, and for not lining up private funding ahead of the announcement. Some banking experts said that the bank would have managed its risks better had it not been for the Economic Growth, Regulatory Relief, and Consumer Protection Act (EGRRCPA), enacted in 2018 and supported by SVB CEO Greg Becker, which reduced the frequency and number of scenarios of required stress testing implemented under the Dodd–Frank Wall Street Reform and Consumer Protection Act for banks with under $250 billion in assets. The Federal Reserve Bank of San Francisco did have discretion to annually examine any bank with $100 billion in assets.
== Development == In early embryogenesis, the esophagus develops from the endodermal primitive gut tube. The ventral part of the embryo abuts the yolk sac. It is very small in the beginning, but it lengthens due to descent of lungs and heart. During the second week of embryological development, as the embryo grows, it begins to surround parts of the sac. The enveloped portions form the basis for the adult gastrointestinal tract. The sac is surrounded by a network of vitelline arteries. Over time, these arteries consolidate into the three main arteries that supply the developing gastrointestinal tract: the celiac artery, superior mesenteric artery, and inferior mesenteric artery. The areas supplied by these arteries are used to define the midgut, hindgut and foregut. The surrounded sac becomes the primitive gut. Sections of this gut begin to differentiate into the organs of the gastrointestinal tract, such as the esophagus, stomach, and intestines. The esophagus develops as part of the foregut tube. The esophagus develops as a tube, lined with smooth muscle but continues development craniocaudally into different proportions of striated muscle. Both types of muscle have been demonstrated to be of different precursor cells. The innervation of the esophagus develops from the pharyngeal arches.
Therefore, the feedback that is read by this central regulator could include chemical and mechanical as well as cognitive cues. The significance of each of these factors will depend on the nature of the fatigue-inducing work that is being performed. Though not universally used, "metabolic fatigue" is a common alternative term for peripheral muscle weakness, because of the reduction in contractile force due to the direct or indirect effects of the reduction of substrates or accumulation of metabolites within the myocytes. This can occur through a simple lack of energy to fuel contraction, or through interference with the ability of Ca2+ to stimulate actin and myosin to contract.
He also contributes regularly to scholarly journals through research, studies, letters, and fatwas, supervises academic theses at the master’s and doctoral levels, and teaches students of Islamic knowledge in ongoing lessons and study circles.
==== Liver and gastrointestinal ==== Hepatobiliary MRI is used to detect and characterize lesions of the liver, pancreas, and bile ducts. Focal or diffuse disorders of the liver may be evaluated using diffusion-weighted, opposed-phase imaging and dynamic contrast enhancement sequences. Extracellular contrast agents are used widely in liver MRI, and newer hepatobiliary contrast agents also provide the opportunity to perform functional biliary imaging. Anatomical imaging of the bile ducts is achieved by using a heavily T2-weighted sequence in magnetic resonance cholangiopancreatography (MRCP). Functional imaging of the pancreas is performed following administration of secretin. MR enterography provides non-invasive assessment of inflammatory bowel disease and small bowel tumors. MR-colonography may play a role in the detection of large polyps in patients at increased risk of colorectal cancer.
Sources: en.wikipedia.org
To have a better chance of detecting Type III artificial sources, Calissendorff suggests taking several photographs in a row, fast enough to fix the movement of turbulence in the atmosphere, applying different photometric filters and looking for dark areas (the case of a Dyson sphere being assembled by a Type II civilization), or analyzing the infrared spectrum of galaxies. A much larger sample of objects should be studied.
presented evidence that in natural S. cerevisiae populations clonal reproduction and selfing (in the form of intratetrad mating) predominate. In nature, the mating of haploid cells to form diploid cells is most often between members of the same clonal population and out-crossing is uncommon. Analysis of the ancestry of natural S. cerevisiae strains led to the conclusion that out-crossing occurs only about once every 50,000 cell divisions. These observations suggest that the possible long-term benefits of outcrossing (e.g. generation of diversity) are likely to be insufficient for generally maintaining sex from one generation to the next. Rather, a short-term benefit, such as recombinational repair during meiosis, may be the key to the maintenance of sex in S. cerevisiae. Some pucciniomycete yeasts, in particular species of Sporidiobolus and Sporobolomyces, produce aerially dispersed, asexual ballistoconidia.
== Management == Due to the susceptibility to infection of mature and overripe fruit, post-harvest treatment of fruit with fungicides is the most common method of combating P. expansum. Proper sanitation and careful handling of the fruit are two non-chemical methods that can help control the disease. Good sanitation reduces contact with orchard soil either on the fruit or in transportation containers. And since the fungus needs a wound to infect, careful handling can reduce infection even when the fungus is present. Chemical treatment with a chlorine bath can be effective in killing spores. Biofungicides using active ingredients such as bacteria and yeast have been successful in preventing infection, but are ineffective against existing infections.
== Further reading == A System of Blood Analysis by Folin and Wu (1919) On the determination of creatinine and creatine in urine by Otto Folin (1914) Recommendations for Improving Serum Creatinine Measurement: A Report from the Laboratory Working Group of the National Kidney Disease Education Program by Gary L. Myers et al. (2006) "Max Jaffé (1841–1911)". Nature. 148 (3743): 110. 1941. Bibcode:1941Natur.148T.110.. doi:10.1038/148110d0.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.